POS0614 INTERLEUKIN-17 MEDIATED INFLAMMATORY AND PRO-FIBROTIC ACTIVITY OF SKIN FIBROBLASTS DERIVED FROM SYSTEMIC SCLEROSIS PATIENTS (SSc) COMPARED WITH HEALTHY CONTROLS (HC)
Authors: G. Aßmann, J. Weghorn, M. Bewarder, F. Gellrich, C. Rittich, C. Pfoehler, F. Neumann
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Systemic sclerosis (SSc) is an autoimmune connective tissue disease defined by fibrosis of skin an internal organs as well as vascular impairment. Furthermore, in addition to the fibrosis several autoimmune features of SSc often show a phenotype of auto-inflammation. As recently published T-cell proliferation and, in particular, T helper 17 (Th17) cells with their cytokine interleukin-17 seem to play an important role in the pathogenesis of the fibro-inflammatory environment of the tissue in SSc. <h3>Objectives</h3> Here we investigated cultures of skin fibroblasts derived from SSc and healthy controls (HC) to evaluate the different expression of pro-inflammatory and pro-fibrotic proteins and cytokines (defined as biomarkers) after stimulation of interleukin-17 (IL-17) and tumor growth factor-beta (TGF-β), measured by concentrations in the cellular supernatant. <h3>Methods</h3> The current study was approved by the Ethics Committee at the Saarland University, all participants of the study gave their written informed consent for their participation in the study. SSc patients (n = 8, aged 43 to 65 years) and healthy controls (n = 4, aged 40 to 53 years) underwent a skin biopsy of the lateral abdominal wall. Fibroblasts isolated from the surgical samples were cultured for 5-8 passages according to standard procedures. The cells were stimulated by 25 ng/ml of IL-17 or 2.5 ng/ml of TGF-β for 48 h. The supernatant of the different fibroblast cultures was analysed for the following biomarkers: pro-inflammatory cytokines such as interleukin-1-beta, interleukin-6 (IL-6), interleukin-8 (IL-8), preferentially anti-fibrinolytic and/or pro-fibrotic proteins such as matrix metalloproteinase-1 (MMP-1), monocyte chemotactic protein 1 (MCP-1), procollagen, insulin-like growth factor-binding protein 3 (IGFPB-3), and Lysyloxidase-1 (LOX-1). The concentrations of these biomarkers were analysed applying commercial ELISA standard tests (IL-1β, IL-6, IL-8, MCP-1, MMP-1, procollagen, and IGFBP-3). The differences between SSc and HC (without and after stimulation with IL-17 or TGB-β, respectively) were statistically analysed by t-test (with fisher`s correction). <h3>Results</h3> IL-6, MCP-1 and procollagen secreted by native fibroblasts showed a significant higher concentration in SSc compared to HC in unstimulated conditions. In contrast, the anti-fibrotic efficient protein MMP-1 reached a significant lower concentration in SSc-derived fibroblasts, the significant differences between SSc and HC could also be reproduced after IL-17 stimulation (Table 1), whereas after stimulation with TGF-β the differences between SSc and HC were only significant for IL-6 and MCP-1. The remaining proteins and cytokines which were investigated (IL-1-β, IGFPB-3, LOX-1) do not resulted in significant differences. <h3>Conclusion</h3> Skin fibroblasts in SSc patients showed significantly stronger pro-inflammatory and pro-fibrotic properties compared with healthy controls as an indication of the fibro-inflammatory character of the disease. Furthermore, the significant increase of the expression of IL-6, MCP-1, procollagen and the decrease of the anti-fibrotic efficient protein MMP-1 after IL-17 stimulation suggests IL-17 as a well promising target in SSc. <h3>Reference</h3> [1]Bellando-Randone et al, JSRD (2021) Vol. 6(3) 227-235 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Gunter Aßmann Consultant of: Advisory boards for Novartis, AbbVie, Boehringer Ingelheim, Astrazeneca (2017-2022), Grant/research support from: AbbVie, Jan Weghorn: None declared, Moritz Bewarder: None declared, Finn Gellrich: None declared, Christoph Rittich: None declared, Claudia Pfoehler Consultant of: Advisory boards for AbbVie, Novartis, Astrazeneca, BMS, Frank Neumann: None declared.